Conventionally, a typical method for preventing theft of electronic devices is to, for example, embed a sensor called sensor tag on a piece of merchandise or to attach the merchandise to a carton case, and install a sensor in the doorway of a store to detect and sound a buzzer when the merchandise is removed from a store without releasing the function of the sensor at a cash register. However, the effect raises a question because the sensor tag loses its effect once it is removed, and further the electronic devices are still stolen even when the buzzer goes off.
And, Japanese published unexamined application No. 2007-81669 discloses a method for preventing theft of a television receiver. This invention is to store the contact information of a user on a television receiver, and to inform the user on the fact of theft via a network when the television receiver is determined to be stolen.
Also, the Japanese published unexamined application No. 2001-347894 discloses a theft prevention method for a motor vehicle. In this invention, in-vehicle electrical components are disabled once a vehicle is set to an armed state in case of a theft. Thereafter, the in-vehicle electrical components remain disabled unless the disabled state of the in-vehicle electrical components is released in some way. The method for releasing the in-vehicle electrical components from the disabled state is to match a unique signal stored in the antitheft device on the vehicle and an unique signal stored in a memory provided separately.
Further, U.S. Pat. No. 4,987,594 discloses an invention which disables a radio receiver or a television receiver to prevent these receivers from theft by blocking a reception signal or outputting a sound when there is no permission to use.
However, any of these inventions described above are incomplete for preventing theft of electronic devices from stores. Under this circumstance, an invention which disables merchandise from use when the merchandise is stolen, demotivates thieves, and prevents this type of crime, has been desired.